Recording/playback apparatus

ABSTRACT

A recording/playback apparatus which accommodates in a cassette shell a recording medium and which performs recording and/or playback with respect to the recording medium cassette provided with a cassette-side antenna connected to an in-cassette memory recording information regarding recording contents or the like. The apparatus includes an apparatus side antenna for effecting communication through the in-cassette memory and the cassette-side antenna, wherein an electric wave transmission portion is formed in the portion of the cassette holding member opposed to the cassette-side antenna, and wherein the apparatus-side antenna is arranged in correspondence with the electric wave transmission portion.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/282,016 filed on Oct. 29, 2002, now Patented as U.S. Pat. No.6,950,067, which is a divisional of U.S. patent application Ser. No.09/713,335 filed on Nov. 16, 2000, now Patented as U.S. Pat. No.6,496,314, the contents of each of which are hereby incorporated in itsentirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording/playback apparatus.

2. Description of the Related Art

There is a system which is provided with an in-cassette memory forrecording information regarding recording contents or the like and acassette-side antenna and in which access is gained to the in-cassettememory while keeping the recording/playback apparatus side in anon-contact state.

When reducing the size of a recording/playback apparatus, it isnecessary, from the viewpoint of strength, that the cassette holdingmember, which holds the recording medium cassette and which movesbetween the recording/playback position where recording and/or playbackis effected to and from the recording medium cassette and the cassettepassing position where the passing of the recording medium cassette iseffected between the interior and the exterior of the apparatus, must beformed of a metal.

FIG. 14 shows an example of a coil pattern formed on a printed circuitboard. As shown in FIG. 14, the coil formed on the printed circuit boardis realized by spirally developing the pattern on the printed circuitboard from a terminal (input terminal) a1 on one side of the coilconnected to a tap 211 toward the inner periphery side.

Here, when an attempt is made to connect a terminal (output terminal) b1on the opposite side of the terminal a1 to a tap 213, it is impossibleto lead out the pattern from the side (side A) where the pattern formingthe coil is developed (In the same plane, it is impossible for onepattern to jump over the other pattern so that the two patterns may notcome into contact with each other), so that it is necessary to lead outthe pattern from a terminal a2 of the coil of the side A to the oppositeside (side B) through a through-hole, and to form on the side B apattern indicated by a dashed line, connecting the pattern to theterminal b1 through the through-hole. That is, it is necessary to formthe printed circuit board 1 as a two-layer (double-sided) substrate.Further, in this case, by connecting terminals c2 and c1 in theintermediate portion of the coil by utilizing the side B, it is possibleto prepare a tap 212.

To keep the substrate area small while improving the inductance of thiscoil, a spiral pattern is formed on either of the sides A and B of thedouble-layer substrate, as in the case of a printed circuit board 220shown in FIG. 15 (That is, the number of turns of the coil isincreased). However, in the case of FIG. 15, while taps 221 and 222connected to both ends of the coil can be easily formed, it isimpossible, due to the fact that it is a pattern on a substrate, to forman intermediate tap unless air wiring (for example, wiring using ajumper line).

Thus, if an improvement in inductance is to be achieved with a smallsubstrate area, and further, if an intermediate tap is to be provided,another layer is added to form a three-layer structure to form a patternfor the intermediate tap on the printed circuit board, whereby, as inthe case of a printed circuit board 230 shown in FIG. 16, it is possibleto mount taps 231 through 233 without performing air wiring. In the caseof the example shown in FIG. 16, an intermediate terminal a2 is formedbetween the input terminal a1 connected to the tap 231 and the outputterminal b1 connected to the tap 233, and this intermediate terminal a2is connected to the tap 232 through the terminal c1.

When a coil formed on a substrate is used, for example, in a circuit ofan antenna used in radio communication, electromagnetic couplingnon-contact communication or the like, the power last step circuit onthe transmission side is in many cases formed as a push-pull circuit,and, to supply transmission power to the coil, it is more advantageousthat an intermediate tap be formed in the coil. FIG. 17 shows an exampleof a coil of a transmission apparatus using a coil having nointermediate tap (the printed circuit board 220 described with referenceto FIG. 15) in electromagnetic coupling non-contact communication.

Drive signals of normal and reverse phases are emitted by signal sourcesV1 and V2 in FIG. 17. These signals are increased in power bytransistors Q1 and Q2 and resonated at a predetermined communicationfrequency by a capacitor C3. The values of capacitors C1 and C2 andresistors R1 through R7 are determined by the characteristics of thecircuit. The DC voltage applied to the collectors of the transistors Q1and Q2 is supplied through choke coils L1 and L2, and the connectionpoint of the choke coils L1 and L2 undergoes decoupling by a choke coilL3 and a capacitor C2. The radiation of the output signal is maximum ina direction perpendicular to the printed circuit board 2. Further,transistors Q3 and Q4 are used for the purpose of buffering.

There is a technique, as shown in FIG. 24, in which signals aretransmitted and received in a non-contact state between a communicationapparatus 301 having an antenna 303 and a communication apparatus 302having an antenna 304 by utilizing the electromagnetic couplinggenerated between the antennas 303 and 304. When the antennas 303 and304 of the communication apparatuses 301 and 302 consist of ordinary RCLcircuits, as shown in FIG. 25, the equivalent circuits of the antennas303 and 304 are as shown in FIG. 26. The communication conducted betweenthe antennas 303 and 304 is effected by the mutual inductance M.

Impedances Z1 through Z5 in FIG. 26 are as follows: Z1 corresponds tothe impedance 1/jωC1 of the capacitor C1 of the antenna 303; Z2corresponds to the synthetic impedance R1+jω(L1−M) consisting of theresistance R1 of the antenna 301 and the inductance L1−M obtained bysubtracting the mutual inductance M from the inductance L1; Z3corresponds to the impedance jωM corresponding to the mutual inductanceM; Z4 corresponds to the synthetic impedance R2+Jω(L2−M) consisting ofthe resistance of the antenna 2 and the inductance L2−M obtained bysubtracting the mutual inductance M from the inductance L2; and Z5corresponds to the impedance 1/jωC2 of the capacitor C2 of the antenna302.

In the circuit shown in FIG. 26, assuming that the current flowingthrough the impedance Z2 is i1 and that the current flowing through theimpedance Z5 is i2, the currents i1 and i2 can be expressed by thefollowing formulas 1 and 2.i1=−SEin×Z1/{Z1+Z2+Z3(Z4+Z5)/(Z3+Z4+Z5)}  (1)i2=i1×Z3/(Z3+Z4+Z5)  (2)

-   -   Here, S indicates the mutual susceptance of the amplifier        driving the antenna 301. Thus, −SEin indicates the total current        of the circuit.

And, the voltage E2 applied to both ends of the antenna 302 is expressedby the following formula 3.E2=i2×Z5=i1×Z3×Z5/(Z3+Z4+Z5)  (3)

From formulas 1 through 3, the reciprocal of amplification degree D,which is the inverse number of the amplification degree G, is obtainedas shown by the following formula 4.D=1/G=Ein/E2={−1/(S×Z1×Z3×Z5)}×{(Z1+Z2+Z3)(Z3+Z4+Z5)−Z32}  (4)

Here, assuming that both the primary circuit and the secondary circuitare resonating, the resonance frequency ωO is expressed by the followingformula 5.ω₀=1/√{square root over (L ¹ C ¹ )}=1/√{square root over (L ² C ²)}  (5)

And, the voltage E2 applied to both ends of the antenna 302 is expressedby the following formula 3.E2=i2×Z5=i1×Z3×Z5/(Z3+Z4+Z5)  (3)From formulas 1 through 3, the reciprocal of amplification degree D,which is the inverse number of the amplification degree G, is obtainedas shown by the following formula 4.D=1/G=Ein/E2={−1/(S×Z1×Z3×Z5)}×{(Z1+Z2+Z3)(Z3+Z4Z5−Z32}  (4)

Here, assuming that both the primary circuit and the secondary circuitare resonating, the resonance frequency ωO is expressed by the followingformula 5.ω₀1/√{square root over (L ¹ C ¹ )}=1/√{square root over (L ² C ² )}  (5)

And, assuming that the coupling coefficient is k, k is expressed by thefollowing formula 6 from the values of the mutual inductance M and theinductance L1 and the inductance L2 of the antenna 301 and the antenna302.

Further, assuming that the Q (quality factor) at the time of resonanceis Q1 in the primary circuit and Q2 in the secondary circuit, Q1 and Q2are expressed by the following formulas 7 and 8.Q1=(ωOL1/R1  (7)Q2=(ωOL2/R2  (8)

Thus, assuming that the loss factor d is d1 in the primary circuit andd2 in the secondary circuit, the loss factor d1 and the loss factor d2are expressed by the following formulas 9 and 10.d1=1/Q1  (9)d2=1/Q2  (10)

Assuming that the detuning factor indicating the difference between theactual communication frequency ω and the resonance frequency ωO is x,the detuning factor x is expressed by the following formula 11.x=(ω−ωO)/ωO  (11)

Here, it is the proximity to the resonance point that is in question, sothat the following formula 12 holds true.ω≈ω₀  (12)

Thus, by substituting formulas 5 through 12 into formula 4 andperforming arrangement, formula 13 is obtained.

$\begin{matrix}{D = {\frac{- j}{s\;\omega_{0}\sqrt{L_{1}L_{2}}} \times \frac{1}{k}\left\{ {{\left( {d_{1} + {2{jx}}} \right)\left( {d_{2} + {2{jx}}} \right)} + k^{2}} \right\}}} & (13)\end{matrix}$

Here, regarding the frequency characteristics of the reciprocal ofamplification gain, the absolute value of 1/k{(d1+j2x){d2+j2x}+k2},which is the variable portion of formula 12, is to be considered, sothat the following formula 14 is used as the frequency characteristicsof the reciprocal of amplification gain y.

$\begin{matrix}{y = {\frac{1}{k}\sqrt{{16x^{2}} - {4\left( {{2k^{2}} - d_{1}^{2} - d_{2}^{2}} \right)x^{2}} + \left( {k^{2} + {d_{1}d_{2}}} \right\}^{2}}}} & (14)\end{matrix}$

The maximum point and the minimum point at the point of inflection ofthe frequency characteristics (communication efficiency) are points atwhich dy/dx=0 in formula 14, so that the maximum point is expressed bythe following formulas 15 and 16, and the minimum point is expressed bythe following formulas 17 and 18.x0=0  (15)y0=(k2+d1d2)/k  (16)

$\begin{matrix}{x_{b} = {{\pm \frac{1}{2}}\sqrt{\frac{{2k^{2}} - \left( {d_{1}^{2} + d_{2}^{2}} \right)}{2}}\;\left( {1 \geq k \geq \sqrt{\frac{d_{1}^{2}\mspace{20mu} d_{2}^{2}}{2}}} \right)}} & (17) \\{y_{b} = {\frac{d_{1} + d_{2}}{2k}\sqrt{{4k^{2}} - \left( {d_{1} - d_{2}} \right)^{2}}}} & (18)\end{matrix}$

Further, the optimum coupling coefficient kO providing the maximum gain(that is, at the time of critical coupling) is k, which provides therelationship dy0/dk=0 when formula 16 is differentiated with respect tok, so that the optimum coupling coefficient k0 is expressed by formula19.k _(o) =√{square root over (d ¹ d ² )}=1/√{square root over (Q ¹ Q ²)}  (19)

The yO at that time can be obtained by substituting formula 19 intoformula 16. Formula 20 shows the value of yO at the time of criticalcoupling.y ₀=2√{square root over (d ¹ d ² )}  (20)

Thus, the gain GO is expressed by formula 21.

$\begin{matrix}{G_{o} = \frac{s\;\omega_{o}\sqrt{L_{1}L_{2}Q_{1}Q_{2}}}{2}} & (21)\end{matrix}$

Assuming that the antenna 303 and the antenna 304 are of the sameperformance, d1=d2 =d=kO and y0=yb=2d.

FIG. 27 shows the transfer frequency characteristic y when, in formula11, the coupling coefficient k is k<kO, k=kO, and k>kO. It can be seenfrom FIG. 27 that when the coupling coefficient k satisfies therelationship k<kO, y exhibits a single peak characteristic, and as kapproaches kO, the value of y when x=0 decreases. When k>kO, thetransfer frequency characteristic y from the antenna 303 to the antenna304 changes from the single peak characteristic to a wavy (double peak)characteristic, and the maximum value of the communication efficiency(that is, the minimum value of the transfer frequency characteristic y)at the time of critical coupling (k=kO) is the same as that at the timeof wavy characteristic (k>kO). Further, the voltage value E1 of theantenna 1 exhibits substantially the same characteristic. As can be seenfrom these facts, the critical coupling point kO being the border, evenwhen k decreases, the passing range center frequency level decreases,and the communication efficiency deteriorates. That is, it can be seenthat communication is difficult to perform when the non-contact distance(inter-antenna distance) is too small or too large.

The inter-antenna coupling coefficient k is determined by the antennaconfiguration, the relative distance, etc., while, as shown in formula19, the critical coupling condition kO is determined by the Q1 and theQ2 of the antenna 303 and the antenna 304. Thus, by adjusting the Q ofthe antenna, it is possible to some degree to control the transferfrequency characteristic, for example, whether the transfer frequency ata certain coupling coefficient k exhibits a single peak characteristicor a wavy characteristic. That is, by effecting binary variation of thevalue of this Q in accordance with the information to be transmitted, itis possible to effect transmission and reception of information betweenthe antennas by utilizing ASK (amplitude shift keying).

Generally speaking, as compared with the communication apparatus 301,the communication apparatus 2 is devoid of a power source and retainsthe spreading of the ASK band and rectifies a high-frequency signal toutilize it as the power source for itself, so that the degree ofmodulation is set to be low modulation. When information is transferredfrom the communication apparatus 2 to the communication apparatus 301,the Q2 of the antenna 304 is equivalently varied in accordance with theinformation to be transmitted, so that the resistance R2 of the antenna304 is turned ON/OFF (FIG. 25). When information is transmitted from thecommunication apparatus 301 to the communication apparatus 2, thecircuit current value of the antenna 303 is varied in accordance withthe information to be transmitted. The mutual communication is performedon a time division basis (semi-double system). While the communicationapparatus 301 is transmitting a signal, the Q2 of the communicationapparatus 302 is fixed, and while the communication apparatus 302 istransmitting a signal, the circuit current value of the communicationapparatus 301 is fixed.

FIG. 28 shows the transfer frequency characteristic (the output voltagewith respect to the communication frequency) when the resistance R2 ofFIG. 25 is turned OFF when the information signal bit is 0 and turned ONwhen the information signal bit is 1. When the carrier signal frequencyis in the proximity to 13.56 MHz (point c), a signal exhibiting anamplitude variation corresponding to the turning ON/OFF of theresistance R2 is supplied to the antenna 303 of the communicationapparatus 301. The difference in this transfer amplitude is the ASKsignal obtained at the communication apparatus 301. Although in thiscase, a binary variation is achieved through a combination of the wavycharacteristics, it is possible, in some cases, to achieve a binaryvariation through a combination of a wavy characteristic and asingle-peak characteristic.

Incidentally, when a recording medium cassette is held by a cassetteholding member, if there is a metal portion in the portion opposed tothe cassette-side antenna, the radio wave is not propagated in asatisfactory manner even if the recording/playback-apparatus-side, i.e.,the apparatus-side antenna, is opposed to the cassette-side antenna, sothat the communication cannot be performed in a satisfactory manner.

Further, when the size of the recording/playback apparatus is to bereduced, the cassette holding member has to be formed of a metal fromthe viewpoint of strength.

SUMMARY OF THE INVENTION

In view of this, it is an object of the present invention to make itpossible to reduce the size of a recording/playback apparatus whichperforms communication in a non-contact state to and from an in-cassettememory recording information regarding recording contents or the like.

To achieve the above object, there is provided, in accordance with thepresent invention, a recording/playback apparatus comprising arecording/playback mechanism portion performing recording and/orplayback with respect to a recording medium cassette, a cassette holdingmember which holds the recording medium cassette, which moves between arecording/playback position near the recording/playback apparatus whererecording and/or playback is conducted with respect to the recordingmedium cassette and a cassette passing position spaced apart from therecording/playback mechanism portion where the passing of the recordingmedium cassette is effected, and at least the portion of which opposedto the cassette-side antenna is formed of a metal, a cassette passingmember which moves between a holding position where the recording mediumcassette is held by the cassette holding member and an eject positionwhere the recording medium cassette is inserted and detached in adirection crossing the movement path of the cassette holding member, andan apparatus side antenna for effecting communication through thein-cassette memory and the cassette-side antenna, wherein an electricwave transmission portion is formed in the portion of the cassetteholding member opposed to the cassette-side antenna, and wherein theapparatus-side antenna is arranged in correspondence with the electricwave transmission portion.

Thus, in the recording/playback apparatus of the present invention, thecommunication between the cassette-side antenna and the apparatus-sideantenna is conducted efficiently, and, further, the cassette holdingmember can be formed by using a metal, so that it is possible to reducethe size of the recording/playback apparatus.

As described above, when the coil formed by the development of thepattern on the printed circuit board is realized in a two-layersubstrate, a coil having an intermediate tap and sacrificing inductance(a coil whose number of turns is small) is selected, as in the case ofthe printed circuit board 201 described with reference to FIG. 14.However, when a large inductance is to be obtained, it is necessary toselect a coil which is not provided with an intermediate tap, as in thecase of the printed circuit board 220 described with reference to FIG.15. When a coil which is not provided with an intermediate tap is used,for example, in the antenna of a transmission circuit in radiocommunication, electromagnetic coupling communication or the like, it isnecessary to provide external choke coils L1 and L2 for supplying powerto the antenna, as in the case of the circuit described with referenceto FIG. 17, resulting in an increase in cost and expansion of circuitscale. Further, in the case in which a three-layer substrate is used toprovide an intermediate tap while improving the inductance of the coil,as in the case of the printed circuit board described with reference toFIG. 16, the substrate cost increases due to the increase in the numberof layers of the substrate. Further, due to the increase in thesubstrate thickness, it is difficult to realize a thin antenna, such asa card-type antenna.

The present invention has been made in view of the above problem. It isan object of the present invention to improve the reactance, forexample, in a printed circuit board in which the number of two-layersubstrates is small, and further make it possible to provide anintermediate tap.

The printed circuit board disclosed in Claim 1 is characterized in thaton one and the other side of the printed circuit board, a plurality ofpatterns forming the coil are developed concentrically.

In the printed circuit board disclosed in Claim 1, the plurality ofpatterns forming a coil on one and the other side of the printed circuitboard are developed concentrically.

However, as shown in FIG. 28, as the carrier signal frequency approaches13.097 MHz (point a), the difference in amplitude with respect to theON/OFF of the resistance R2 decreases, and the degree of modulation ofASK decreases. And, when the carrier signal frequency reaches 13.097 MHz(point a), the difference in amplitude disappears, and it is impossibleto transmit a signal from the communication apparatus 302 to thecommunication apparatus 301. This point will be referred to as the“modulation null point”. Further, at 14.262 MHz (point b), a troublesimilar to that at 13.097 MHz (point a) is generated. When thismodulation null point is passed, it is again possible to obtain amodulation signal. Although the 0/1 polarity at the time of modulationis inverted, it is all bits that are inverted, so that this can beeasily coped with on the reception side, making it possible to decodecorrectly the data.

While in the case described with reference to FIG. 28 the communicationfrequency is changed, a similar trouble also is generated in the case inwhich the communication frequency is fixed and there is a variation inthe resonance frequencies of the antennas. FIG. 29(A) shows theexamination result of the practical communication distance when theantenna resonance frequency of the antenna 303 of the communicationapparatus 301 is tuned to the communication frequency 13.56 MHz, and avariation is caused to occur in the antenna resonance frequency of theantenna 304 of the communication apparatus 302, and FIG. 29(B) shows theexamination result of the practical communication distance when theantenna resonance frequency of the antenna 303 of the communicationapparatus 301 is tuned to the communication frequency 14.1 MHz, and avariation is caused to occur in the antenna resonance frequency of theantenna 304 of the communication apparatus 302.

As described above, when the distance between the communicationapparatus 301 and the communication apparatus 302 is too deviated fromthe critical coupling point (for example, when the inter-antennadistance is over 4 mm) and when it is too close to the critical couplingpoint (for example, when the inter-antenna distance is shorter than 1.4mm), whatever value the resonance frequency of the antenna 302 may take,a communication trouble is generated. However, communication troublegenerated in other cases is a communication trouble due to themodulation null point. That is, communication trouble in the portionwhere the resonance frequency of the antenna 304 of the communicationapparatus 302 is 12.63 MHz at the resonance frequency 13.56 MHz of theantenna 303 of the communication apparatus 301 and where thecommunication distance is near 2.3 mm (the portion indicated by a inFIG. 29(A)), and communication trouble in the portion where theresonance frequency of the antenna 304 of the communication apparatus302 is 13.84 MHz at the resonance frequency 14.1 MHz of the antenna 303of the communication apparatus 301 and where the communication distanceis near 2 mm to 2.6 mm and 3 mm to 3.6 mm (the portion indicated by band c in FIG. 29(B)), are generated due to the modulation null point.

In this way, when there is a variation in the antenna resonancefrequency of the communication apparatus 301 and the communicationapparatus 302, communication is possible or impossible depending uponthe communication distance.

Further, when the value of the Q of the antenna to increase thecommunication distance, the modulation null point is more easilygenerated in the proximity to the target communication frequency.Further, assuming that the permissible value of the variation in thegeneral-purpose parts constituting the antenna is, for example, ±5%, thepossibility of these troubles being generated is very high, so that itis difficult to realize a con-contact communication which is highlyreliable with no adjustment.

The present invention has been made in view of the above problem. It isan object of the present invention to realize a con-contactcommunication which is highly reliable with no adjustment by checkingthe transmission/reception condition, selecting an appropriate resonancefrequency from a plurality of resonance frequencies depending on thechecking result, and effecting switching automatically.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view which shows, together with FIGS. 2 through4, an example of a tape cassette used in the recording/playbackapparatus of the present invention in a state in which the lid is at theclosed position;

FIG. 2 is a perspective view showing the lid in an open state;

FIG. 3 is a perspective view showing the lid in the open state frombelow;

FIG. 4 is an enlarged view showing a memory substrate, of which portion(a) is an external view and portion (b) is an internal view;

FIG. 5 is a schematic perspective view which shows, together with FIGS.6 through 13, an embodiment of the recording/playback apparatus of thepresent invention in a state in which the cassette holder is at an ejectposition;

FIG. 6 is a schematic perspective view showing a state in which thecassette holder is lowered to a holding position which is on a slidechassis at a cassette passing position;

FIG. 7 is a schematic perspective view showing a state in which theslide chassis is drawn into the recording/playback apparatus togetherwith the cassette holder;

FIG. 8 is a schematic perspective view showing the outer contour of theslide chassis;

FIG. 9 shows an apparatus-side antenna, of which portion (a) is aninternal view and portion (b) is an external view;

FIG. 10 is a block diagram showing a communication circuit;

FIG. 11 is a schematic perspective view showing a state in which a tapecassette is inserted into the cassette holder at the eject position;

FIG. 12 is a schematic perspective view, partially cutaway, which showsthe state shown in FIG. 11 from a different angle;

FIG. 13 is a schematic perspective view, partially cutaway, which showsthe state in which the cassette holder holding the tape cassette islowered and positioned at the holding position;

FIG. 14 is a diagram showing a relevant example of a coil formed throughpattern development on a printed circuit board;

FIG. 15 consisting of 15A ad 15B is a diagram showing a relevant exampleof a coil formed through pattern development on a printed circuit board;

FIG. 16 consisting of 16A and 16B is a diagram showing a relevantexample of a coil formed through pattern development on a printedcircuit board;

FIG. 17 is a circuit diagram of a communication apparatus inelectromagnetic coupling non-contact communication using the printedcircuit board of FIG. 2;

FIG. 18 consisting of 18A and 18B is a diagram showing a firstembodiment of a printed circuit board to which the present invention isapplied;

FIG. 19 is a diagram illustrating the position of a coil and anintermediate tap formed on the printed circuit board of FIG. 18;

FIG. 20 is a circuit diagram of a communication apparatus inelectromagnetic coupling non-contact communication using the printedcircuit board of FIG. 18;

FIG. 21 consisting of 21A and 21B is a diagram showing a secondembodiment of a printed circuit board to which the present invention isapplied;

FIG. 22 is a diagram illustrating the position of a coil and anintermediate tap formed on the printed circuit board of FIG. 21;

FIG. 23 consisting of 23A and 23B is a diagram showing a thirdembodiment of a printed circuit board to which the present invention isapplied;

FIG. 24 is a diagram illustrating a communication apparatus performingelectromagnetic coupling non-contact communication;

FIG. 25 is a diagram illustrating the circuit of the antenna of arelevant communication apparatus performing electromagnetic couplingnon-contact communication;

FIG. 26 is a diagram showing equivalent circuits of the antenna 303 andthe antenna 304 of FIG. 25;

FIG. 27 is a diagram showing the relationship between the couplingcoefficient k and the transfer frequency characteristic y;

FIG. 28 is a diagram showing the relationship between the output voltageand the communication frequency;

FIG. 29 consisting of 29A and 29B is a diagram showing the influence ofvariation in communication distance and reception side resonancefrequency in relevant electromagnetic coupling non-contactcommunication;

FIG. 30 is a block diagram showing a communication apparatus to whichthe present invention is applied;

FIG. 31 is a block diagram showing a communication apparatus to whichthe present invention is applied;

FIG. 32 is a diagram illustrating the circuit of the antenna of acommunication apparatus to which the present invention is applied;

FIG. 33 is a flowchart illustrating the processing of switching the tuneof an antenna;

FIG. 34 is a diagram illustrating inter-antenna distance and tuneswitching;

FIG. 35 is a diagram showing the influence of variation in communicationdistance and reception side resonance frequency in electromagneticcoupling non-contact communication to which the present invention isapplied; and

FIG. 36 is a block diagram of the communication apparatus of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the recording/playback apparatus of the present inventionwill now be described with reference to the accompanying drawings. Theembodiments shown perform recording and/or playback with respect to atape cassette consisting of a cassette shell accommodating a magnetictape as the recording medium.

First, the tape cassette used in the recording/playback apparatus of thepresent invention will be described.

A tape cassette 10 includes a thin box-like cassette shell 20 rotatablyaccommodating tape reels 40 and 50, around which a magnetic tape 30 iswound, and is provided with a front lid covering the front side of aportion of the magnetic tape 30 positioned along the front side of thecassette shell 20 and a back lid 70 covering the rear side of themagnetic tape 30, and the back lid 70 is formed integrally with theforward end of a slider 80 supported by the cassette shell 20 so as tobe movable in the longitudinal direction, and, further, the front lid 60is rotatably supported by the slider 80.

The cassette shell 20 is formed as a thin box and formed of plastic, anda large recess 21 called a mouth portion is formed in the front portionof the cassette shell 20. The mouth portion 21 is open in the front sideand the upper and lower sides. And, a portion of the magnetic tape 30 ispositioned along the front side of the mouth portion 21.

In the bottom plate of the cassette shell 20, there are formed reel baseinsertion holes 22, and when the tape cassette 10 is attached to therecording/playback apparatus, a reel base provided in therecording/playback apparatus is inserted into the cassette shell 20through the reel base insertion holes 22, and engagement shafts providedon the reel base are engaged with reel base engagement holes 40 a and 50a formed in the tape reels 40 and 50 so as to be open on the lower side.

On the inner side of a left-hand side surface portion 61 of the frontlid 60, there is arranged a lid lock member 90, and when it is not used,the lid lock member 90 locks the front lid 60 in a closing positioncovering the front side of the magnetic tape 30.

In the cassette shell, there is arranged a memory substrate. Insubstantially the central portion of an inner side surface 101 of thememory substrate 100, there is mounted a memory chip 110, and anin-cassette memory is formed by the memory chip 110. And, acassette-side antenna 120 is integrally formed on the memory substrate100. That is, on the inner side surface 101 and the outer side surface102 of the memory substrate 100, there are formed spiral antennapatterns 121 and 122, and these antenna patterns 121 and 122 areconnected through a through-hole 123 to form the cassette-side antenna120, the cassette-side antenna 120 being connected to the in-cassettememory 110. And, the outer side surface 102 of the memory substrate 100faces the exterior through a facing hole 23 formed in the back surfaceof the cassette shell 20.

A recording/playback apparatus 130 is provided with a main chassis 140,a slide chassis 150, a movable frame 160 and a cassette holder 170. And,these components are accommodated in an outer casing (not shown).

The main chassis 140 is provided with main mechanisms for drawing themagnetic tape 30 out of the cassette shell 20, forming a predeterminedtape path and causing the tape to run, etc., such as a rotary head drum141 and tape draw-out guides 142, constituting a recording/playbackmechanism portion for performing recording and playback with respect tothe tape cassette 10.

The slide chassis 150 is positioned on the front side of the mainchassis 140 and supported so as to be movable in the longitudinaldirection with respect to the main chassis 140. The slide chassis 150 isformed such that side plates 152 are raised from the right and left sideedges of a bottom plate 151 consisting of a metal plate and a frontplate 153 is raised from the front edge of the bottom plate 151. And, asubstantially rectangular opening 153 a is formed at a position nearerto one side portion of the front plate 153.

A cosmetic panel 154 is formed of a materials such as plastic, which isnon-magnetic and non-conductive but which transmits an electric wave,and is mounted so as to cover the front side of the front plate 153.

The above-described tape cassette 10 is attached to the slide chassis150, forming a cassette holding member that is moved between arecording/playback position where it is drawn into the main chassis 140to perform recording and playback with respect to the tape cassette 10and a passing position where it is drawn out of the main chassis 140 toperform the passing of the tape cassette between it and the cassetteholder 170, reel bases 155, etc. to be engaged with the tape reels 40and 50 to rotate them being provided. And, the reel bases 155 haveupwardly protruding reel engagement shafts 155 a.

The movable frame 160 includes a substantially rectangular, frame-liketop surface portion 161, from the right and left side edges of whichside plates 162 downwardly protrude, the rear end portions of the sideplates 162 being rotatably supported by the rear end portion of the mainchassis 140 and upwardly biased by a torsion coil spring 163. Guideslits 162 a extending in the longitudinal direction are formed in theside plates 162.

Substantially the front half portions at the upper ends of the sideplates 171 of the cassette holder 170 are connected by a front top plate172, and the rear end portions of the side plates 171 are connected by arear end top plate 173. Receiving plates 174 protrude from the loweredges of the side plates 151 so as to approach each other.

And, the cassette holder 170 supported by the movable frame 160 so as tobe movable in the longitudinal direction. Further, slide pins 175protruding from the side plates 171, which are members supporting thecassette holder 170 on the movable frame 160, are slidably engaged withguide slits 162 a of the movable frame 160.

One end portions of rotary links 180 are rotatably connected to theportions of the side plates 171 of the cassette holder 170 protrudingfrom the lower edges of the side plates 162 of the movable frame 160,and the other end portions of the rotary links 180 are rotatablysupported by the front plate 153 of the slide chassis 150.

This slide holder 170 constitutes a cassette passing member movingbetween a holding position where the tape cassette is held by the slidechassis 150 and an eject position where the tape cassette 10 is insertedand detached.

The memory chip (in-cassette memory) 110 is a passive device whichperforms control processing after receiving an electric wave, and isformed as a so-called battery-less component having no power source.Thus, it is provided with a power source circuit, a control circuit, amemory, etc. obtaining power by electromagnetic induction.

In correspondence to this, the recording/playback apparatus 130 isprovided with an apparatus-side antenna 190 for performing communicationwith the in-cassette memory 110 through the cassette-side antenna 120.In the apparatus-side antenna 190, spiral antenna patterns 192 areformed on both sides of the antenna substrate 191: These antennapatterns 192 are connected by a through-hole 193, and one antennapattern 192 is connected directly and the other antenna pattern 192 isconnected through the through-hole 193 to the terminals 194. And, theapparatus-side antenna 190 is attached to the front plate 153 such thatthe antenna patterns 192 are positioned in correspondence with theopening 153 a of the front plate 153 of the slide chassis 150.

And, the recording/playback apparatus 130 has a communication circuit200 for performing recording and reading of information with respect tothe in-cassette memory 110 through the apparatus-side antenna 190 andthe cassette-side antenna 120; and, the communication circuit 200 isprovided with an R/W portion 201, a data processing portion 202 and acontrol portion 203. That is, the R/W portion 201 performs modulationand amplification of the signal supplied to the apparatus-side antenna190, demodulation of the signal obtained from the apparatus-side antenna190, etc., the data processing portion 202 performs data processing suchas coding of the signal transmitted to the R/W portion 201, decoding ofthe signal received from the R/W portion 201 or CRC, and the controlportion 203 is formed, for example, by a microcomputer, and performsgeneral control such as the controlling of the above communication, theoperation of the recording/playback apparatus 130 and display. By thiscommunication circuit 200, information recording with respect to thein-cassette memory 110 and the reading of the information recorded inthe in-cassette memory 110 is performed. And, the apparatus-side antenna190 is connected to the R/W portion 201 of the communication circuit 200through the terminals 194.

As described above, the in-cassette memory 110 is formed as abattery-less component, so that it is necessary to provide between thecassette-side antenna 120 and the apparatus-side antenna 190electromagnetic coupling which is sufficient for effecting data transferand power transfer. Thus, to secure the communication distance, aconstruction which cuts off or restricts the magnetic path by metal isnot desirable. In the above recording/playback apparatus 130, theapparatus-side antenna 190 is arranged in correspondence with theopening 153 a of the front plate 153 of the slide chassis 150, so thatthere is nothing to cut off the magnetic path, making it possible tosecure a sufficient electromagnetic coupling between the apparatus-sideantenna 190 and the cassette-side antenna 120.

The opening 153 a of the front plate 153 of the slide chassis 150 isprovided so as not to cut off the magnetic path, so that, if there is aproblem such as a deterioration in strength due to the formation of theopening, it is possible to cover the opening 153 a with a material whichis non-magnetic and non-conductive and which transmits an electric wave,for example, a plastic plate.

Further, when the cosmetic plate 154 is formed of a material which ismagnetic and conductive and which does not easily transmit an electricwave, such as a metal plate, an opening is provided at a position incorrespondence with the apparatus-side antenna 190, thereby making itpossible not to cut off the magnetic path.

Next, the recording/playback operation using the tape cassette 10 willbe described.

The movable frame 160 rotates upwardly and, in a condition in which thecassette holder 170 is at the eject position shown in FIG. 5, the tapecassette 10 is inserted into the cassette holder 170 (See FIGS. 11 and12). By inserting the tape cassette 10 into the cassette holder 170, thetape cassette 10 is held in the space formed by the side plates 171, thetop plates 172 and 173 and the receiving plates 174, and the lock of thefront lid 60 by the lid lock member 90 is cancelled. The front lid 60rotates upwardly, and the front lid 60 and the slider 80 (together withthe back lid 70) are moved rearwardly, the portion of the magnetic tape30 positioned in front of the mouth portion 21 is opened the upperportion of the mouth portion 21 is opened.

Next, when the movable frame 160 is downwardly rotated, the cassetteholder 170 also descends; when the cassette holder 170 descends to theholding position at the lowermost end of the descent range (See FIG.13), the reel bases 155 provided in the slide chassis 150 are insertedinto the cassette shell 20 through the reel base insertion holes 22, andthe reel engagement shafts 155 a of the reel bases 155 are engaged withthe reel engagement holes 40 a and 50 a of the tape reels 40 and 50.Further, the tape draw-out guides 142, the pinch roller (not shown),etc. are positioned inside the mouth 21.

Further, in the condition shown in FIG. 13, the outer side surface ofthe cassette-side antenna 120 of the tape cassette 10 is opposed to theinner side surface of the apparatus-side antenna 190 provided on thefront plate 153 of the slide chassis 150, and communication is possiblebetween the recording/playback apparatus 130 and the in-cassette memory110 of the tape cassette 10. Thus, in this recording/playback apparatus130, the slide chassis 150 is drawn into the main chassis 140 (See FIG.7), and it is possible to read the contents of the in-cassette memory110 or to write information to the in-cassette memory 110 beforerecording and playback with respect to the tape cassette 10 is possible.In the condition in which the slide chassis 150 is at the cassettepassing position in which it is drawn out of the main chassis 140, it ispossible to hold the front plate 153 close to the front side of theouter casing, that is, to hold the apparatus-side antenna 190 close tothe front side of the outer caging, so that when the front side of theouter casing is non-magnetic and non-conductive or even when it is notso, the portion opposed to the apparatus-side antenna 190 is kept as anelectric wave transmitting portion, whereby, even if the tape cassette10 is not attached to the recording/playback apparatus, by opposing thecassette-side antenna 120 to the apparatus-side antenna 190 through thefront side of the outer casing, it is possible to perform communicationwith the in-cassette memory 110 of the tape cassette 10 by driving thecommunication circuit 200. Thus, it is possible to know the recordingcontents of the tape cassette 10, etc. before the tape cassette 10 isattached to the recording/playback apparatus 130.

Next, the slide chassis 150 moves inwardly with respect to the mainchassis 140, and reaches a predetermined draw-in position, that is, therecording/playback position.

And, when the slide chassis 150 reaches the recording/playback position,the tape draw-out guides 142, the pinch roller, etc. move topredetermined positions to draw the magnetic tape 30 out of the cassetteshell 20, winding the magnetic tape 30 around the rotary head drum 141at a predetermined winding angle and forming a predetermined tape path.

When recording or playback with respect to the magnetic tape 30 iscompleted, the components such as the tape draw-out guides 142 and thepinch roller move into the mouth portion 21, and the excess magnetictape 30 is taken up on one tape reel 40.

Then, the slide chassis 150 is returned to the cassette passingposition, and the movable frame 160 rotates upwardly and the cassetteholder 170 is positioned at the eject position. Then, the tape cassette10 is drawn out of the cassette holder 170.

In the above recording/playback apparatus 130, the opening 153 a isformed in the metal portion corresponding to the portion where theapparatus-side antenna 190 is positioned, so that a sufficientelectromagnetic coupling is obtained between the apparatus-side antenna190 and the cassette-side antenna 120, and the communication between thecassette-side antenna 120 and the apparatus-side antenna 190 isconducted efficiently, whereby it is possible to form the slide chassis150, which is the cassette holding member, of a metal, so that it ispossible to reduce the size of the recording/playback apparatus 130.

The configurations and structures of the portions of the above-describedembodiment are only given by way of example, and they should not beconstrued as restricting the technical scope of the present invention.

FIG. 18 shows the first embodiment of the printed circuit board to whichpresent invention is applied. A printed circuit board 240 is adouble-layer substrate; FIG. 18(A) is a pattern diagram of side A of theprinted circuit board 240, and FIG. 18(B) is a perspective view of thepattern of side B of the printed circuit board 240 as seen from side A.

In the printed circuit board 240, two sets of spiral patterns, two onside A and two on side B, are developed concentrically. The spiralpattern (the solid line pattern of FIG. 18(A)) extending from a terminal(input terminal or output terminal) a1 connected to a tap 241 toward thecenter (inner periphery) is connected to side B through a through-holea2, and, from the through-hole a2, a spiral pattern extending toward theouter periphery (the solid line pattern of FIG. 18(B)) is developedtoward a through-hole c1 connected to a tap 242. This pattern isconnected to side A again through the through-hole c1, and the spiralpattern (the dotted line pattern of FIG. 18(A)) extending from thethrough-hole c1 toward the center is connected to side B through athrough-hole c2, and, from the through-hole c2, a spiral pattern (thedotted line pattern of FIG. 18(B)) extending toward the outer peripheryis developed toward a through-hole (output terminal or input terminal)b1 connected to a tap 243.

The patterns of sides A and B of the printed circuit board 240, in planeform, are as shown in FIG. 19. That is, in FIG. 18(A), the patternindicated by the solid line corresponds to the coil La1-a2 of FIG. 19;in FIG. 18(A), the pattern indicated by the dotted line corresponds tothe coil Lc1-c2 of FIG. 19; in FIG. 18(B), the pattern indicated by thesolid line corresponds to the coil La2-c1 of FIG. 19; and, in FIG.18(B), the pattern indicated by the dotted line corresponds to the coilLc2-b1 of FIG. 19.

Here, when the printed circuit board 240 is used as the coil of anantenna using a push-pull circuit, the tap 242, which is an intermediatetap, must be exactly a point electrically serving as the middle point.However, the inductance of the coil generated by each of the patterns ofside A and side B of the printed circuit board exhibits a larger valueon the outer periphery side than on the inner periphery side (the coilon the outer periphery side is longer than that on the inner peripheryside). Thus, when the pattern of printed circuit board 240 moves fromside A to side B, the connection is effected such that interchangeoccurs between the inner periphery and the outer periphery.

That is, the A-side pattern from the terminal a1 to the through-hole a2is formed in the outer periphery; the B-side pattern from thethrough-hole a2 to the through-hole c1 is formed in the inner periphery;the A-side pattern from the through-hole c1 to the through-hole c21 isformed in the inner periphery; and the B-side pattern from thethrough-hole c2 to the through-hole b1 is formed in the outer periphery.

And, the inter-tap coils are formed by the A-side coil and the B-sidecoil, and combined such that the entire lengths of the inter-tap coilsare substantially the-same. Thus, as shown in FIG. 19, the portion formthe tap 241 to the tap 242 and the portion from the tap 242 to the tap243 are respectively formed by the A-side and B-side coils, and theinner periphery and outer periphery patterns are combined. As a result,the tap 242 can serve as the electrical middle point between the tap 241and the tap 243.

FIG. 20 shows a circuit diagram of a transmission apparatus inelectromagnetic coupling non-contact communication using the printedcircuit board 240.

As in the transmission circuit described with reference to FIG. 17, inthe transmission circuit of FIG. 20, normal and reverse phase drivesignals are transmitted by a signal source V1 and a signal source V2.These signals are supplied to the base of a PNP transistor Q3 or a PNPtransistor Q4 through a resistor R1 or a resistor R2 and amplified.Then, they are output from an emitter to which DC bias voltage isapplied through a resistor R3 or a resistor R4. This output signal isinput to the base of a PNP transistor Q9 or a PNP transistor Q10 througha resistor R12 or a resistor R11, and amplified in power. Thepower-amplified signal is resonated at a predetermined communicationfrequency determined by a coil (antenna) formed by a capacitor C3 andthe printed circuit board 240.

To the tap 242 of the printed circuit board 240, there is applied a DCvoltage whose AC component is suppressed by the choke coil L3 andsmoothed by the capacitor C2. On the basis of this voltage, a biascurrent flows through the route: the tap 242, the tap 241, thecollector-emitter of the NPN transistor Q9, and the resistor R5, or theroute: the tap 242, the tap 243, the collector-emitter of the NPNtransistor Q10, and the resistor R5. The capacitor C1 is used for thebypassing purpose.

In the transmission circuit described with reference to FIG. 17, DCvoltage is supplied to the transistor Q1 and the transistor Q2, so thatit is necessary to provide external choke coils L1 and L2, and, due tothe variation thereof, it is difficult to supply a stable bias voltage.In the transmission circuit shown in FIG. 20, it is possible to supplythe power source by the tap 202, which can serve as a correct electricalmiddle point, so that it is possible to omit the choke coils L1 and L2,whereby it is possible to reduce the number of parts, reduce the circuitscale, and, at the same time, supply a stable bias voltage.

Next, FIG. 21 shows the second embodiment of the printed circuit boardto which the present invention is applied. Like the printed circuitboard 240, the printed circuit board 250 is a two-layer substrate; FIG.21(A) is a pattern diagram of side A of the printed circuit board 250;and FIG. 21(B) is a perspective pattern diagram of side B as seen fromside A.

In the printed circuit board 250, two sets of spiral patterns, three onside A and three on side B, are concentrically developed. The spiralpattern (the solid line pattern of FIG. 21(A) extending toward thecenter from a terminal a1 connected to a tap 251 is connected to side Bthrough a through-hole a2, and, from the through-hole a2, a spiralpattern extending toward the outer periphery (the solid line pattern ofFIG. 21(B)) is developed toward a through-hole c1 connected to a tap 52.This pattern is connected to side A through the through-hole c1, and thespiral pattern (the dotted line pattern of FIG. 21(A)) extending fromthe through-hole c1 toward the center is connected to side B through athrough-hole c2, and, from the through-hole c2, the spiral patternextending toward the outer periphery (the dotted line pattern of FIG.21(B)) is developed toward a through-hole d1 connected to a tap 253.This pattern is connected to side A through a through-hole b1, and thespiral pattern extending from a through-hole d1 toward the center (thetwo-dot-chain-line pattern of FIG. 21(A)) is connected to side B througha through-hole d2, and, from the through-hole d2, the spiral patternextending toward the outer periphery (the two-dot-chain-line pattern ofFIG. 21(B)) is developed toward the through-hole b1 connected to a tap254.

The patterns of sides A and B of the printed circuit board 250, in planeview, are as shown in FIG. 22. That is, in FIG. 21(A), the patternindicated by the solid, line corresponds to the coil La1-a2 of FIG. 22;in FIG. 21(A), the pattern indicated by the dotted line corresponds tothe coil Lc1-c2 of FIG. 22; in FIG. 21(A), the pattern indicated by thetwo-dot chain line corresponds to the coil Ld1-d2 of FIG. 22; in FIG.21(B), the pattern indicated by the solid line corresponds to the coilLa2-c1 of FIG. 22; in FIG. 21(B), the pattern indicated by the dottedline corresponds to the coil Lc2-d1 of FIG. 22; and, in FIG. 21(B), thepattern indicated by the two-dot chain line corresponds to the coilLd2-b1 of FIG. 22.

Here, for the tap 252 and the tap 253, which are intermediate taps, tobe exactly points effecting electrical division into three equal partswith respect to the tap 251 and the tap 254, the central pattern shouldhave exactly a middle length with respect to the lengths of the outerperiphery and inner periphery-patterns (½ of the sum total of the lengthof the outer periphery coil and the length of the inner periphery coil).And, a combination is effected such that the inter-tap coil lengths aresubstantially the same. That is, as shown in FIG. 22, in the portionfrom the tap 251 to the tap 252 and the portion from the tap 253 to thetap 254, the inner periphery and outer periphery patterns are combined,and, in the portion from the tap 252 to the tap 253, the central patternis combined. As a result, the tap 252 and the tap 253 are exactly pointseffecting electrical division into three equal parts with respect to thetap 251 and the tap 254.

Similarly, by increasing the number of patterns developed on the samesurface of the printed circuit board, it is possible to provide three ormore intermediate taps on the coil formed in the pattern on the printedcircuit board.

FIG. 23 shows the third embodiment to which the present invention isapplied. For example, in uses other than antennas, in a case in whichthere is no need to mount an intermediate tap on the coil formed on theprinted circuit board, it is possible to apply the present invention toimprove the inductance of the coil formed on the printed circuit boardwithout increasing the substrate area and the number of substrates.

FIG. 23(A) is a pattern diagram of side A of a printed circuit board260, and FIG. 23(B) is a perspective pattern diagram of side B of theprinted circuit board 260 as seen from side A. The printed circuit board260 is a two-layer substrate, and the pattern wiring is substantiallythe same as that of the printed circuit board 240 described withreference to FIG. 18, only the tap 261 and the tap 262 being mounted,and with no intermediate tap being provided. While here two patterns aredeveloped on the same surface, it is also possible to develop three ormore patterns on the same surface, thereby further improving the coilinductance.

FIG. 30 is a block diagram showing the construction of a communicationapparatus 311 and a communication apparatus 312 to which the presentinvention is applied. Here, a communication apparatus is a generalapparatus for transmitting and receiving information by non-contactcommunication, meaning, for example, a VTR, a cassette, a mobile phone,a card, a CAM, etc.

A controller 321 of the communication apparatus 321 generates a readcommand requiring data transmission of a predetermined block of the datathe reception side communication apparatus reserves (for example, datareserved in memory 335 of the communication apparatus 312), and suppliesit to a transmission/reception portion 324 through an inner bus 322 andan input/output interface 23. The transmission/reception portion variesthe circuit current value of an antenna 313, whereby it controls theamplification modulation of the supplied data, transmitting the readcommand from the antenna 313 to the communication apparatus 312.

And, when the communication apparatus 312 receives the read command andreceives the relevant read response (that is, a predetermined block datareserved in the memory 335 of the communication apparatus 312) throughthe antenna 313, the transmission/reception portion 324, theinput/output interface 323, and the inner bus 322, the controller 321decides that the communication is being normally conducted; and executesdata communication. When the read response with respect to the readcommand is not received, the controller 321 outputs a control signal forchanging the resonance frequency of the antenna 313 through the innerbus 322 and the input/output interface 323 to the transmission/receptionportion 324. Upon the input of the control signal from the controller321, the transmission/reception portion 324 changes the resonancefrequency adjusting voltage of the antenna 313 to change the resonancefrequency (change the resonance capacitance) of the antenna 313.

As described with reference to FIG. 29, the modulation null point at acertain resonance frequency and the modulation null point at a resonancefrequency in proximity thereto are generated in differentinter-apparatus distances at different resonance frequencies of thereception side apparatus. Thus, by changing the resonance frequency ofthe transmission side apparatus in accordance with the resonancefrequency on the reception side and the inter-apparatus distance, it ispossible to eliminate the communication trouble due to the modulationnull point. In the communication apparatus 311, it is possible to setone frequency or a plurality of sub-frequencies (sub-tune), which is avalue obtained by offsetting the frequency by approximately 500 KHz to 2MHz with respect to the main resonance frequency (main tune) (that is,it is possible to previously set several values of the resonancefrequency adjusting voltage supplied to the antenna 313), and, whilechecking the state of communication with the reception side apparatus inaccordance with the processing described below with reference to FIG.33, it is possible to switch sequentially the resonance frequency(searching). Here, this arrangement in which a stable communication canbe obtained by changing the tune will be referred to as tune diversity.

Further, the controller 321 reads data from, for example, the magneticdisk inserted into the drive 326, the optical disk 342, themagneto-optical disk 343, the semiconductor memory 344, etc. andreserves them in the memory 325 through the input/output interface 323,or reads the data reserved in the memory 325, and supplies then to thetransmission/reception portion 324 through the inner bus 322 and theinput/output interface 323. The transmission/reception portion 324changes the circuit current value of the antenna to control thereby theamplification modulation of the supplied data and transmits the datafrom the antenna 313 to the communication apparatus 312.

Further, the information transmitted from the communication apparatus312 is received by the antenna 313, modulated by thetransmission/reception portion 324, and input to the controller 321through the input/output interface 323 and the inner bus 322. Thecontroller 321 causes the input data to be reserved in the memory 325,or, when the input data is the read response, it decides that thecommunication is being normally conducted.

In the communication apparatus 312, the data transmitted from thecommunication apparatus 311 are received by the antenna 314, modulatedby the transmission/reception portion 331, and supplied to thecontroller 334 through the input/output interface 332 and the inner bus333. The controller 334 executes a processing according to the supplieddata, and, as needed, causes the supplied data or the data generated bythe executed processing to be reserved in the memory 335. In the memory335, predetermined data used to check the transmission/receptioncondition with respect to the communication apparatus 311 are reserved.

For example, when the read command is received from the communicationapparatus 311, the controller 334 receives the data reserved in apredetermined block of the memory 335, and supplies them to thetransmission/reception portion 331 through the inner bus 333 and theinput/output interface 332. The transmission/reception portion 331switches ON/OFF the resistor R12 of the antenna 314i described belowwith reference to FIG. 32, in accordance with the supplied data, wherebyit controls the amplification modulation of the supplied data (ASK), andtransmits the data from the antenna 314 to the communication apparatus311.

Further, the drive 336 also is connected to the input/output interface332, and the controller 334 performs interchange of data, for example,with the magnetic disk 341 inserted into the drive 336, the optical disk342, the magneto-optical disk 343, and the semiconductor memory 344.

The power source generating portion 337 generates the power sourcenecessary for the operation of the communication apparatus 312 byrectifying the received signal and supplying it to each portion of thecommunication apparatus 312.

When the reception side apparatus is a very small communicationapparatus, such as a card, a construction may be adopted which is notprovided with a drive or an input/output interface, as in the case ofthe communication apparatus 351 shown in FIG. 31(A). The antenna 352 andthe transmission/reception portion 361 or the power source generatingportion 364 of the communication apparatus 351 execute the sameprocessing as the antenna 314, the transmission/reception portion 331,the controller 334, the memory 335, and the power source generatingportion 337 of the communication apparatus 312 described with referenceto FIG. 30, so that a description thereof will be omitted here.

Further, when the reception side communication apparatus is acommunication apparatus of the size, for example, of a mobile phone, itis difficult to provide a built-in drive, etc., so that, as in the caseof the communication apparatus 371 shown in FIG. 31(B), it is possibleto adopt a construction in which an external devices such as a drive,can be externally connected by providing a network interface 386. Theconstruction of the communication apparatus 371 is the same as that ofthe communication apparatus 312 described with reference to FIG. 30except that the network interface 386 is provided instead of the drive336 of the communication apparatus 312, so that a description thereofwill be omitted here.

FIG. 32 shows in detail the construction of the antenna 313 and theantenna 314 of the communication apparatus 311 and the communicationapparatus 312. The antenna 313 and the antenna 314 are basically of thesame construction as the case described with reference to FIG. 32 exceptthat, to make it possible to change the resonance frequency of theantenna 313, a variable capacitance diode (varicap) D11 is used insteadof the capacitor C1 of the antenna 303, and that an input for changingthe application voltage E11 of the variable capacitance diode D11 isadded to the cathode side of the variable capacitance diode D11. Avariable capacitance diode is an element which has a characteristic suchthat when a reverse direction bias is applied, the capacitance betweenanode and cathode varies according to the voltage value. Thetransmission/reception portion 324 of the communication apparatus 311changes the resonance frequency of the antenna 313 by controlling thecapacitance thereof by varying the voltage E11 applied to the variablecapacitance diode D11 in the processing described below with referenceto FIG. 33.

Next, with reference to the flowchart of FIG. 33, the searchingprocessing of the antenna diversity of the communication apparatus 311will be described.

In step S1, the controller 321 transmits to the communication apparatus312 a read command, which is a signal instructing the communicationapparatus 312 to read the data of a predetermined block reserved in thememory 335 of the communication apparatus 312 and to return the to thecommunication apparatus 311 through the inner bus 322, the input/outputinterface 323, the transmission/reception portion 324, and the antenna313. When the antenna 314 of the communication apparatus 312 can receivethis read command, the received the signal is supplied to the controller334 through the transmission/reception portion 331, the input/outputinterface 332, and the inner bus 333, and the controller 334 reads thedata from the designated block of the memory 335 in accordance with theread command, and transmits the data to the communication apparatus 311as the read response through the inner bus 333, the input/outputinterface 332, the transmission/reception portion 331, and the antenna314. When the antenna 314 cannot receive the read command, the readresponse is not transmitted from the communication apparatus 312 to thecommunication apparatus 311.

In step S2, the controller 321 makes a judgement as to whether the readresponse has been received or not on the basis of the data input throughthe antenna 313, the transmission/reception portion 324, theinput/output interface 323, and the inner bus 322. When it is decided instep S2 that the read response has been received, the controller 321decides in step S3 that the communication with the communicationapparatus 312 is possible, and executes the communication of data. And,the procedure returns to step S1, and the processing from there on isrepeated.

When it is decided in step S2 that the read response has not beenreceived, the controller 321 generates in step S4 a control signal forchanging the resonance frequency of the antenna 313 to a resonancefrequency other than the current resonance frequency and outputs it tothe transmission/reception portion 324 through the inner bus 322 and theinput/output interface 323. When, for example, two resonance frequenciesof main tune and sub-tune are previously prepared in the communicationapparatus 311, this control signal issues an instruction to change theresonance frequency to sub-tune if the communication is being performedin main tune and to change the resonance frequency to main tune if thecommunication is being performed in sub-tune. The transmission/receptionportion 324 changes the resonance frequency of the antenna 313 bychanging the value of the voltage for adjusting the resonance frequencyapplied to the variable capacitance diode D11 of the antenna 313 inaccordance with the input control signal. And, the procedure returns tostep S1, and the processing from there onward is repeated.

Here, to illustrate the processing of changing the resonance frequencyby tune diversity, a case will be considered with reference to FIG. 34in which the distance between the antenna 313 of the communicationapparatus 311 and the antenna 314 of the communication apparatus 312varies.

For example, a case will be considered in which the inter-antennadistance is gradually decreased from the condition in which theinter-antenna distance is not less than 5 mm and in which it is decidedthat communication trouble is generated in both main tune and sub-tune.Here, in the communication apparatus 311, two resonance frequencies ofmain tune and sub-tune are set, the main tune being set somewhat higherthan the communication frequency in order to improve the practicalcommunication distance, and the sub-tune being set at a frequency higherthan the main tune approximately by 500 kHz in order to compensate forthe communication trouble due to the modulation null point in the maintune.

When the inter-antenna distance is not less than 4.2 mm, it is decidedthat communication trouble has been generated, so that the communicationapparatus 311 executes searching. When the inter-antenna distance isgradually reduced to attain 4.2 mm, the main tune is a more advantageousfrequency in communication distance, so that in the inter-antennadistance indicated by AO in the drawing, it is possible to executecommunication in main tune.

When the inter-apparatus distance is further reduced to attain 3.6 mm,the modulation null point is reached at the frequency of the currentmain tune, and communication trouble is generated. That is, if thecommunication apparatus 311 transmits the read command, thecommunication apparatus 312 does not return the read response. Thecontroller 321 outputs to the transmission/reception portion 324 acontrol signal for changing the resonance frequency to sub-tune, and thetransmission/reception portion 324 causes the value of the voltageapplied to the variable capacitance diode D11 to be changed, adjusts theresonance frequency to sub-tune, and transmits the read command to thecommunication apparatus 312. In sub-tune, normal communication ispossible (as indicated at B2 in the drawing) even when the inter-antennadistance is 3.0 to 3.6 mm, so that the communication apparatus 312,having received the read command, returns the read response to thecommunication apparatus 311. And, the communication apparatus 311 andthe communication apparatus 312 start normal communication. After this,also, when communication trouble is generated through change ininter-antenna distance, the controller 321 executes tune by controllingthe value of the voltage applied to the variable capacitance diode D11,always maintaining a condition in which communication is possible.

In this way, also in the case in which the communication conditionvaries with a change in the inter-antenna distance, the communicationapparatus 311 automatically selects and sets a resonance frequency atwhich communication is possible, whereby it is possible to maintain asatisfactory communication state without the user having to perform atuning operation or an adjustment.

FIG. 35 shows the practical communication distance examination resultsin a case in which a variation is effected in the antenna resonancefrequency of the antenna 314 of the communication apparatus 312,executing tune diversity with the antenna resonance frequency of theantenna 313 of the communication apparatus 311 being the main tune of13.56 MHz, which is the communication frequency, and the sub-tune of14.1 MHz.

For example, when the normal communication cannot be conducted at theresonance frequency of 13.56 MHz, which is the main tune, (that is,when, in the case described above with reference to FIG. 29(A),communication trouble indicated at a is generated), the resonancefrequency is changed to 14.1 MHz by tune diversity, and when the normalcommunication cannot be conducted at the resonance frequency of 14.1MHz, which is the sub-tune, (that is, when, in the case described abovewith reference to FIG. 29(B), communication trouble indicated at b and cis generated), the resonance frequency is changed to 13.56 MHz by tunediversity. In other words, it can be seen that the examination resultshown in FIG. 35, in which tune diversity is used, is equal to what isobtained by synthesizing the portions of the examination results shownin FIGS. 29(A) and 29(B) in which communication is possible.

As can be seen from FIG. 35, in the communication apparatus to which thepresent invention is applied, by using tune diversity, the communicationtrouble at the modulation null point is eliminated, making it possibleto execute highly reliable communication without performing anadjustment.

The software for executing the above series of processing is installedfrom a recording medium to a computer in which the program constitutingthe software is incorporated in the dedicated hardware (for example, thecontroller 321 and the controller 334 of FIG. 30), or, for example, to ageneral-purpose personal computer capable of executing various functionsby installing various programs.

As shown in FIG. 30, this recording medium is composed of a packagemedia including the magnetic disk 341 (including the floppy disk) onwhich the program is recorded, the optical disk 342 (including CD-ROM(compact disk-read only memory), the DVD (digital versatile disk)), andthe magneto-optical disk 343 (including MD (mini-disk), or a packagemedia consisting of the semiconductor memory 344 or the like,distributed for the purpose of providing the user with a program apartfrom the computer.

Further, in this specification, the steps describing the programrecorded on the recording medium include not only the processingconducted in time sequence according to the order described, but alsothe processing which, if not processed in time sequence, is executed inparallel processing or individually.

As is apparent from the above description, in accordance with thepresent invention, there is provided a recording/playback apparatuswhich accommodates in a cassette shell a recording medium and whichperforms recording and/or playback with respect to the recording mediumcassette provided with a cassette-side antenna connected to anin-cassette memory recording information regarding recording contents orthe like, the apparatus comprising a recording/playback mechanismportion performing recording and/or playback with respect to a recordingmedium cassette, a cassette holding member which holds the recordingmedium cassette, which moves between a recording/playback position nearthe recording/playback apparatus where recording and/or playback isconducted with respect to the recording medium cassette and a cassettepassing position spaced apart from the recording/playback mechanismportion where the passing of the recording medium cassette is effected,and at least the portion of which opposed to the cassette-side antennais formed of a metal, a cassette passing member which moves between aholding position where the recording medium cassette is held by thecassette holding member and an eject position where the recording mediumcassette is inserted and detached in a direction crossing the movementpath of the cassette holding member, and an apparatus side antenna foreffecting communication through the in-cassette memory and thecassette-side antenna, wherein an electric wave transmission portion isformed in the portion of the cassette holding member opposed to thecassette-side antenna, and wherein the apparatus-side antenna isarranged in correspondence with the electric wave transmission portion.

Thus, in the recording/playback apparatus of the present invention, thecommunication between the cassette side antenna and the apparatus-sideantenna is conducted efficiently. Further, the cassette holding membercan be formed by using a metal, so that it is possible to achieve areduction in the size of the recording/playback apparatus.

In the printed circuit board of the present invention, a plurality ofpatterns forming coils are concentrically developed on one and the otherside of the printed circuit board, so that, in a printed circuit boardwhose number of layers is small, for example, a two-layer substrate, itis possible to achieve an improvement in reactance and provide anintermediate tap.

In the communication apparatus, the communication method, and therecording medium program of the present invention, the resonancefrequency of the antenna is set, the transmission/reception state isdetected, and the resonance frequency of the antenna is changed inaccordance with the detection result, so that the transmission/receptionstate is checked, and, in accordance with the checking result, anappropriate resonance frequency is selected from a plurality ofresonance frequencies and switched automatically, whereby it is possibleto realize a reliable non-contact communication without performingadjustment.

In the communication apparatus, the communication method, and therecording medium program of the present invention, the data used todetect the transmission/reception state in the communication with theother communication apparatus are reserved, and when the requirement totransmit data is received from the other communication apparatus todetect the communication state, the data are transmitted to the othercommunication apparatus, so that it is possible to cause the othercommunication apparatus in the data communication to check thetransmission/reception state, making it possible to realize a reliablenon-contact communication without performing an adjustment.

As shown in FIG. 36, a communication apparatus 311 or 312 performs datatransmission/reception with another communication apparatus. Thecommunication apparatus 311 or 312 includes setting means 902 forsetting an antenna resonance frequency, detection means 904 fordetecting the transmission/reception state and changing means 906 forchanging the resonance frequency of an antenna set by the setting meansin accordance with the detection result of the detection means. Thedetection means 904 transmits transmission requirement of predetermineddata to the other communication apparatus and detects thetransmission/reception state on basis of whether the predetermined datahas been received from the other communication apparatus or not.

1. A communication device that communicates data with other communication devices, the communication device comprising: an antenna; setting means for setting a resonance frequency of the antenna; detection means for detecting a transmission/reception state; and changing means for changing the resonance frequency of the antenna based on a detection result of the detection means, wherein the detection means transmits an instruction to one of the other communication devices send predetermined data, and detects the transmission/reception state based on whether the predetermined data has been received from the one of the other communication devices, and wherein the changing means sequentially switches the resonance frequency of said antenna. 